Electric discharge tube



Aug. 20, 1935. J. G. w-. M ULDER ELECTRIC DISCHARGE TUBE Filed July 7, 1951 jnvenfor: e]: G. ZaMuZaZer,

Patented 20, 1935 ELECTRIC DISCHARGETUBE; 1

q ifllohannes:GijsbertusWilhelm.Miilden-Eindhoven, 7 Netherlands, assignor to N. V. Philips Gl'oeilampenfabriekem' Eindhoven, Netherlands T i J pplication July 7, 1931, Serial No: 54927911? Inthe Netherlands July 9, 1930 r2 Claims. (01. 250-;275)

This invention relatesto electric discharge tubes and more particularly't'o a rectifying tube in which oneo'r more shields are provided be tween the cathode and one'or 'more' anodes, the hollowside of said the cathode.

shields being turned towards Notwithstanding the presence of shields in dischargetubes of this type in which the shield often entirely surrounds the cathode like a sleeve, which is apertured only at ends turned awayfrom the anode, theref occurssometimes a discharge in the wrong 7 direction {between the anode and cathode, which is probably not due to phenomena occurring outside the tubef I 1 According to "the invention this drawback is avoided by positioningeach anode and the corresponding shield or shields in such a manner with respect to each other and to the cathode that the distance traversed by the electrons'passing from also obtained if the anode is placed symmetrically relative tothe cathode, whereas the shield is mounted asymmetrically with respect to the cathode. v

If the shield longitudinally surrounds the oathode like a sleevej'which' is either closed or which has only a slit in a portion turned away fromthe anode, according to the invention, the anode is dpreferably so disposed with, respect to the can -'ode,that its axisfalls outside of the plane which is perpendicular to the cathode and passes through the centre thereof, said axis however beingfparallel to said plane. A similar result is obtained if one end of the sleeve extends further beyond its incandescent cathode than the "other end.--- V V 'Ihedesiredasymmetry-may also be obtained 'by'shaping either the anode or the shield themselves. I

' Furthermore, in order to obtain or to improve the asymmetry, it is'aclvantageous to use one or more'additional shieldsby which the anode is screened with respect to part of. the cathode or with respect to the shield surrounding the cathode. I

1 The invention will be more'clearly' understood by reference to the accompanying drawing, rep-- resenting,"by way of zexampleysome embodiments thereof. .1 p

Figfl shows an electric discharge tube in which theanode is mounted asymmetrically. l.

Fig. l -a is aisectional side view'of the cathode portion of Figure 1. I 1.6 In Fig.-'2 a shield is positioned asymmetrically. IJIn' Fig. 3 the shield itself is shapedq'asymmetri cally.,i j'jj; InFig. 1 thefldischarg'e tube is'denoted'by1 I One end of this tube is provided with .aist'emi having a pinch 3, and the other end comprises a stem 4 having a pinch 5; .An anode 6. consisting, for example, of graphite or metal, is mounted on the pinch 3.. The terminal wire I is surrounded by an'aenvelope il which permits'of avoiding. disintegration of saidqwirer Thislenvelopeisconstituted, for example; by .astube made of steatite, one end of which is sealed to the glasskofsthe pinch 3, whereas the other endis attached tothe back wall of theanode by'means'oi a baked ,fire-- proof 'ceramicmaterials, Itis'also possiblegto form the whole coating of ceramic material which is baked .on-the pole wire. The incandescent cathode H is'mounted on the pinch Softhe'stem 4 byineans ofthewires Sand 10 which serve at thesame time as supply" conductors. This-cathode mayj be constituted; for example; by. a core I wire, on whichsamaterial; for example barium oxideiis provided in asuitable manner, said oxide material emitting-electrons at-a low temperature.

If desired, the filament'itself may be so prepared,

for-example by being allowed at the-surface with metals emitting electrons 'ata low temperature,

that the emission of the filament is s'uflicient without the provision of a; separate oxidelayeri. Though the drawing showsa. directly heated 'denum and whichfis secured-at the bottom "to the supportingwires l3 and M: As shown in Fig. I'w thesleeve it has a closed cross section. One of these supporting wires 'is connected to awire 15 which is sealedinto thepinchiand leads iout maybe; used, for: example as an ignition device by producing a separate dischargebetween the sleeve and. the incandescent cathode, or'by'connecting the sleeve to the 'mainanodesfi across .a resistance or acondnsen-Itds known that such: a sleeve-permits close spacing of 'the'anode and the cathode relative to each other; if the of the tube and by means of which a definite potential may be applied tothesleeve. I The-sleeve to i discharge tube serves to rectify a relatively high tension and without the risk of aback discharge. It has been found, however, that in some rare cases such discharges may yet occur. This drawback may be entirely avoided, when the anode is not positioned centrally above the sleeve, but is disposed outside of such central position. In this case the xpath o'i the electrons passing from one open end of the shield tothe anode is consequently materially shorter than that of the electrons passing from the other end. The same result is obtained in Fig. 2 in which one end; of the shield extends further beyond the cathode I I than does the other end. In7the drawing corresponding parts are given 'the'same numerals.

- Fig. 3 shows a form of construction which" the screen l2 has substantially the same shape as that shown in Fig. .1 but at the bottom end 'a slit of considerable width is provided. The asymmetry or in other words the shorter'path'for the=electrons passing from cneend of v the" shield to the anode as compared with the path of the electrons passing from the other end "obtained by removing a part 'of the shield atw-I'G so that :the path to the anodeiis shortened at this point.

Though the forms of constructions'illustrated relate to discharge tubes having-only one anode it will be obvious, that these forms of construction are alsopossible iiapluralityof anodes is 1 provided.

Furthermore various "other modifications are; possible, Yfor example, difierent shapes of the anode or "ofthe shield 12, without departing from the *principle of the invention. Finally the shields used'rer increasing the asymmetry referred to in the preambleof the description' may begiven various-difierent constructions. .7 a

what Iclaim is: 1 I 1. Ame'lectric discharge device -"comprising an envelope, an anodaan "elongated cathode and a cylindrical shield around-said cathoda'said shield intercepting tne discharge path between the oathend.

ode and the anode with an imperforate portion which, regarded hem the side of the anode, extends overan arc in-"excess ofl'20l" on each side of that line which represents the shortest dis- -twice between the anode and the cathode, said shield being open at-its two ends'to' provide zaroun'd said =fopen ends two definite discharge paths betweentner cathode and the anode, one

or which is considerably shorter than the other. 2. .An electric discharge device comprising an envelope; an'anode, an elongatedcathode and a cylindrical 'shield around said cathode, said shield lntercepting the discharge pathxbetween the cath- 'ode and the anode and having .an imperfora'te lpoi tion which extends in the direction opposite'to the anode *considerablybeyond a plane which passes through theaxis of thecathode and which plane is substantially perpendicularv to the discharge Tpath, said shield being open at its two ends to. provide two definite discharge paths between'the'cathode and the anode, one of which is ronsiderabw shoiter than the other; '3; An electric rectifier tube comprisinga con- -tainer','electrodes therein, including an anode and an incandescible cathode; and an open-ended and. closed cross-section shield disposed between the anode and the cathode, said shield preventing discharge between said anode and the cathode except at its two open ends, the discharge path between the cathode and the anode being greater around one end of the shield than around its 4 An. electric discharge device comprising a 7 container, an elongated incandescible cathode, and an anode disposed perpendicularly to the axis of said cathode, an elongated sleeve having a closed cross-section interposed between said cathto each other and providing for a longer discharge path between the cathode and the anode at one x-endof the sleeve than at the other end.

5. An electric discharge device comprising a container,- e lectrodes therein including an elongated anode and-an incandescible cathode, and

a sleeve surrounding the cathode and being placed symmetrically with respect to the cathode, the

:axisiof said anode being outside that plane which is perpendicular to the axis of the cathode and which'passes through the middle of the cathode, saidanode-axis being parallel tosaid :plane. j

6. An'electfricrectifier device comprising a'container, '-electrode s therein including an elongated anode and an incandescible cathode and a cyl-' indrical sleeve surrounding the cathode and ;be-' ing placed symmetrically with respect to'the-cathode, the a i xof said anode lying outsideof that plane which is perpendicular tothe axis of the cathode and which plane passes-through themiddle of the cathode, said sleeve having an imperforate portion which viewed from the anode extends over an arc in excess of 1 20; on each side of the unintercepted discharge path betweenthe anode and the cathode. 'j' .1

electric discharge device, comprising a container, electrodes therein includingan anode and an-elongated cathode, anda shield mounted between the anodeand the cathode and extendingalong the full length of the "cathode, said shield --having -a curved surface turned towards the cathode, the axis of the anode substantially passing through the center of the cathode, said shield being mounted asymmetrically with respect to said axis, and-providing a singledefinitedischargepathj i 8. -An electric rectifier tube comprising a icontainer, electrodes therein including-an anode and a cathode, and a cylindrical imperforate shield -provided between'the anode and the cathode, said shield hai ing a curved surface turned towards the cathode and being mounted asymmetrically relative to the cathode, the anode being placed symmetrically with respect to the cathode.

V 9. An electricdischarge device comprising a container, electrodes thereinincluding an anode and a cathode, and a shield provided between ,thejanodeandthe cathode,'-said shield having acurved'surface turned towards the cathode and having a completely closed cross section, and beingmounted asymmetrically with respect to the I cathode.

-1 O.;An electric discharge device comprising a I container, electrodes therein including an-anode and an incandescible cathode, and a shield pro- ;vided between the anode and the cathodegsaid and tan incandescible cathode, and asleeve. surrounding the cathode, said sleeve being imper- ,-forate except at itsqportioniarthest away from the anode, one end of .the sleeve extending .far- 5 ther beyond the cathode than the other end, the anode being placed symmetrically relative to the cathode.

12. An electric discharge device comprising an envelope, an anode, a cathode and. an imperforate screening sleeve having a substantially closed cross-section and beinginterposed between the anode andthe cathode, and disposed around said cathode, said vshield being open at its two ends, and 'at one end being shortened to provide a two discharge paths between the cathode and the anode around said open ends, the discharge path around the shortened end being shorter than- 5 the harge path around the other end. I v I J OHAN NES GIJSBERTUS WILHELM 'MULDER. 

